Daf Yomi Insights - Berachos 19

The Shela haKadosh writes (עשרה מאמרות ר"א) that overdoing actions that are permissible is forbidden. Don't eat too much, or engage in too much intercourse, or talk too much. The Torah did not discuss this explicitly because it is impossible to explain every detail, as each person is different, and it would have required 1,000 details and a personalized Torah for each individual. Even for each person the rules change depending on circumstances. If all people and all times were the same then the Torah would have written, "This much you can eat, this much you can't eat." Instead the Torah just said to be holy and not over indulgent. If something appears to be more than you need at this moment, step away from it. With regards to intercourse as well, it depends on the person's nature, some have a more active libido, some less, as well as timing makes a difference. With regards to speaking about mundane matters the Torah can't possibly say, "Say this, don't say that," because something might be important for one person to say and not for another.
This is the concept of קדש עצמך במותר לך, sanctify yourself with what is permitted. Even though it is permitted, do not over indulge. Following these dictates does not make one an ascetic, it is actually an obligation, but the details aren't written as they are different for each individual. Similarly, when it comes to those things that we are meant to do the Torah just says רק חזק ואמץ, be strong and diligent, because diligence cannot be legislated as it is different for each individual and circumstance.
This is why we find the concept (Berachos 19) of אדם חשוב שאני, that a prominent person is different. He is obligated to act differently than others. If the nature of all people was identical, then it would be a Halacha in the Torah, since they are not we refer to these things as לפנים משורת הדין, beyond the letter of the law. But in reality, they are obligations.